Project Summary/Abstract During pregnancy and delivery women experience pelvic soft tissue injury. This injury is associated with the development of symptomatic pelvic floor disorders (PFDs) including pelvic organ prolapse, urinary, and fecal incontinence. One of the biggest barriers to preventing birth injury and the subsequent sequelae of PFDs is our lack of understanding of when and how injury occurs. Simulation models suggest that term delivery requires stretch to the maternal pelvic floor musculature to a degree greater than that which skeletal muscle can normally undergo without sustaining injury. Thus, with term vaginal birth, near universal injury would be expected. Previous studies have used anatomic and functional methodology to explore this neuromuscular injury, but we continue to lack a complete understanding of maternal pelvic floor injury and recovery patterns. We also possess limited knowledge of the changes which maternal soft tissues undergo during pregnancy, presumably to facilitate atraumatic birth. Our institution houses the SQUID Array for Reproductive Assessment (SARA) system, a novel and noninvasive tool to assess biomagnetic signals such as those created by depolarization occurring with muscle contraction. We propose to use the SARA system to record the biomagnetic signals generated by the levator ani muscles (LAMs) of the maternal pelvic floor. These magnetomyographic (MMG) recordings will be used to study maternal pelvic floor neuromuscular function before and after delivery. Our project will be the first to use MMG technology to assess the maternal LAMs. We will combine clinical, anatomic, and physiologic endpoints to improve our knowledge of maternal pelvic muscular adaptations and injury recovery patterns using a comprehensive protocol with which we have demonstrated promising preliminary data in nulligravidas. Our overall hypothesis is that MMG will allow detection of maternal LAMs adaptation during pregnancy and identification of injury and recovery patterns postpartum. Aim 1: To extend the feasibility of measuring MMG signals of the LAM complex to pregnancy. Aim 2: To track and characterize the intrapartum change in levator MMG signals from 1st to 3rd trimester pregnancy. Aim 3: To determine MMG patterns of LAM birth injury and recovery and associate MMG evidence of injury with injury visible by transperineal US.